The development and production of nanoparticles has been the focus of research efforts for at least the last ten years with the properties of nanoparticles often exhibiting behavior that bridges the gap between bulk materials and atomic or molecular structures. For example, nanoparticles can exhibit properties that are dependent on the size of particles and properties such as melting temperatures, thermal and/or electrical conductivity, physical hardness and the like can be vastly different when compared to bulk materials having the same chemical composition.
Methods used to produce metal nanoparticles include gas evaporation, mechanical attrition, sputtering, pyrolysis of organometallic compounds, microwave plasma decomposition of organometallic compounds and the like. Plasma decomposition of dry precursor powders has proven to be an effective method for producing nanoparticles since dry precursor powders can simplify material handling concerns, a relatively tight range of particle size can be obtained and acceptable production rates are available. However, previous methods to produce core-shell structured nanoparticles have been limited to methods that suffer from large particle size distribution and low production rates. As such, a process for making core-shell nanoparticles that does not suffer from prior art disadvantages would be desirable.